The present invention relates to a telephone communication system, more specifically to a video-phone system using a cellular phone without the capability of video (motion picture) recording and reproducing, and a camera and display device deployed for public use or on the street.
An exemplary Prior Art is shown in FIG. 13. In the figure, reference numeral 1 is designated to a cellular phone without the capability of moving picture recording and reproducing, 6 to a portable video-phone device, 8 to a cellular phone network, 80 to a voice format conversion server between the cellular phone 1 and the portable video-phone 6.
In the Prior Art, for the communication between the cellular phone 1 without the capability of video recording and reproducing and the portable video-phone 6, only voice communication is provided by the cellular network 8. The voice format conversion server 80 converts format from PCM voice data to digitally compressed voice data and vice versa in order to achieve voice communication.
In a video-phone system disclosed in the Japanese Published Unexamined Patent Application No. 2001-326972 (patent reference #1) entitled as “video-phone system in a mobile multimedia terminal”, which uses the packet communication of the cellular network, a video-phone unit having a personal handy-phone system (PHS) wireless terminal is to be provided in addition to a cellular phone terminal or a cellular phone terminal having a personal handy-phone system (PHS) wireless terminal integrated to ensure the communication line to another video-phone unit. The video-phone unit achieves a video-phone by using the packet communication of a cellular network from the cellular phone through the above mentioned communication line.
Patent Reference 1;
Japanese Unexamined Patent Application Publication No. 2001-326972
In the Prior Art video-phone capability and voice communication are both enabled between two portable video-phone units 6. The communication between a portable video-phone unit 6 and a cellular phone without the capability of video recording and reproducing 1, voice communication only is allowed by using the voice format conversion by the media converter in a service center. Since the cellular phone without the capability of video recording and reproducing 1 has no capability of video recording and reproducing, video-phone communication has been physically impossible.
In the Prior Art disclosed in the reference #1 “video-phone system in a mobile multimedia terminal”, a user has to possess or rent a cellular phone terminal having a video-phone unit and a personal handy-phone system unit integrated therein. This may force some users to replace their conventional phone unit to a specific cellular phone unit having a personal handy-phone system (PHS) wireless terminal built-in.
The lifetime of battery is so shorter for the practical use since the user needs to have a specific cellular phone terminal having a video-phone unit and a PHS wireless terminal and to turn them on to be connected with both terminals during waiting.
Also this system uses a packet network operating as “best-effort” method, which does not ensure the communication bandwidth, the bandwidth required for the video data may or may not be allocated as well as there is a delay considerable due to the overhead caused by the relaying the cellular phone having a personal handy-phone system (PHS) wireless terminal integrated, resulting in a too high rate of image dropout for a practical use.
As have been described above the conventional cellular phone or the art described in the reference #1 have failed to solve the incompatibility with the portable video-phone and to provide a reasonable bandwidth and sufficiently short delay in order to provide a better service.